.biu-enter {
    height: 100px;
    background-color: powderblue;
    opacity: 0;
}
.biu-enter-active {
    height: 60px;
    background-color: pink;
    opacity: 1;
    transition: all 600ms ;
}
.biu-exit {
    height: 60px;
    background-color: pink;
    opacity: 1;
}
.biu-exit-active {
    height: 100px;
    background-color: powderblue;
    opacity: 0;
    transition: all 600ms ;
}